A 6 kg block is attached to a massless rope that passes over a frictionless pulley. The pulley can be modeled as a uniformly dense solid cylinder with a mass of 4 kg that rotates around an axis passing through its center. The other end of the rope is wound around a uniformly dense solid sphere with a mass of 10 kg and a radius of 6 cm. When released from rest the block will fall and the sphere will rotate as the rope unwinds from it. The rope will pass over the surface of the pulley without slipping. What is the effective mass of this system (in kg)?